A temperature recorder, which does not need any external energy, which optically signals and marks the wanted level of temperature with a screen movement, being released by a bimetal.
There is a need of a simple, clear resettable temperature recorder including a memory capacity, which recorder can be used among others together with different kinds of water purifying processes. A temperature recorder which indicates that the maximum and minimum temperature, respectively, is
A mechanical temperature recorder, having a memory capacity (in order to show that a specific temperature is reached) and with a reset function, can be used within several fields where there is shortage of electricity, batteries and other advanced and expensive equipment.
Clarity means: A marking which is easy to understand even for those not being able to read and for handicapped and weak-sighted persons. A simple symbolic marking is carried out with the aid of a screen pattern technique by that the temperature recorder shows on its outside either a "sad red man" or a "happy green man", which thus functions without specific knowledge of languages.
The temperature recorder can advantageously be used when measuring the temperature of water, liquids, gases and food.
The temperature recorder can be used in different microbiological water purifying processes as pasteurisation of water, where water temperatures are to be heated to 60°Celcius.
The temperature recorder shows a "sad red man" until the water temperature has exceeded x centigrades. When this occurs the recorder alters to show a "happy green man", which indication thereafter remains (this thus being the memory function of the mechanical system) until the restoring button again is pressed and the temperature simultaneously is considerably lower than x centrigrades (hysteresis value).
When using this temperature recorder it is thus not necessary to observe the increase in temperature in order to notice that the desired temperature is reached.
My invention differs from temperature recorders disclosed in previous patents but the closest is
A temperature recorder which is in the form of a pipe, tubular cover or a rectangular box is manufactured in a transparent glass or plastic material.
A circular mechanical pre-stressed bimetallic washer is placed at one end of the pipe, the tubular cover, the box, which washer is designed to change at x centigrades the desired temperature) and thus having required hysteresis.
Hysteresis means the direction dependant temperature difference which is between the change and the return of the shape of the bimetal. By the spring characteristics the bimetal is provided with such a function that its change of shape occurs suddenly by a certain positive reverse coupling.
The bimetal washer is designed as a circular plate with a diameter of e.g. 12,7 mm and having such a pre-stressing that it is convex in relation to the reference side. At a sudden change of the bimetal its shape is changed to a concave shape within a millisecond. When the temperature has dropped according to the hysteresis the bimetal will return again to the original convex shape. This can occur quite repeatedly without jeopardising the operation.
The circular bimetal washer is placed in a suitable shaped seat in a thermally well conductive material, e.g. aluminium. In this way the washer can be brought to change without being touched, simultaneously as e.g. the water temperature is conducted to the bimetal washer, which means a short delay of the higher temperature from, for instance, the water which is heated. The temperature x centigrades is chosen in dependence on the purification function, e.g. 60 centigrades. The bimetal washer is fixed in a certain position in the tubular cover in which only the pre-determined movement from convex to concave form can be performed.
Inside the tubular cover a piston is placed in the form of a rod, a pipe or a rectangular box, which can run inside the tubular cover. A certain friction is needed in order to prevent the piston from moving out of its position due to influence from the outside. The outside of the piston and the inner side of the tubular cover shall together constitute a braking means.
The piston has a screen pattern of lines, which cover the surface of the piston, completely or partly. This screen pattern can show a picture formed by lines in colour and/or in shape on half of the screen pattern and with face difference of one line, a different picture of lines and/or colour on the second part of a screen pattern. Also other screen pattern solutions having a sharp optical marking and/or change of colours are possible. A screen pattern, coloured lines on a transparent bottom, is arranged on the inner side of the tubular cover. A basic picture is shown in the starting position for the indication of the temperature. For instance a sad mouth in a red-striped face. The change of shape of the bimetal washer will push the piston upwards in the pipe to a fixed stop level when a predetermined temperature is reached, and this should clearly be marked by way of changing the form of a picture and/or changing the colour of a picture. For instance a happy mouth in a green-striped face. When the temperature recorder has this clear optical readable signal, it shows that the desired temperature is reached. The piston will stay in this position by means of the braking means.
The screen pattern function means that both the "sad man" and the "happy man" are traced in each other with screen pattern separation such that for each relative shift of one covering screen pattern a change occurs between the two indications. By the screen patterns being so close to each other the sensitivity towards a parallax distortion is low.
The screen pattern function is maintained by careful definition of the two turning positions of the moveable piston. By an interior carrier being provided with a chosen elasticity between the bimetal washer and the piston, the movement will always be the same, corresponding to the width of the screen pattern, for instance 0,5 mm. The amplitude of the sudden change is somewhat greater, e.g. 0,8 mm.
A magnet is fixed to the upper end of the piston.
A magnet is also fixed on the reset button.
When the reset button on the upper part of the pipe is pressed the magnet on the piston and the magnet on the button will act repulsively against each other and the piston will hereby be pressed backwardly to its initial position. In this way the temperature recorder can be set to 0, where after the temperature recorder again can be used. Another solution for resetting ability to 0 is e.g. to use a spring function.
In order to carry out the reset-operation there is a need for a liquid-proof transmission, as well as a reset-spring action in order to secure the mechanical rest position of the reset-button. These two actions are achieved according to what is said above with a permanent magnet coupling between two small, preferably circular permanent magnets, which are positioned opposite each other with the same polarity. The inner magnet is inside the hermetically closed housing within which also the indication screen pattern and the bimetal are placed, which thus efficiently are protected against liquid, rust etc.
By the repelling force of the two magnets, said spring force is obtained keeping the reset-button in its resting position and also the force being needed to push the screen pattern to its stand-by position ("sad man"). When the temperature has reached x centigrades the bimetal washer changes, whereby the screen pattern moves to the opposite indication ("happy man"). Provided that the temperature again is lower than x centigrades plus the hysteresis value, a repeated pressing of the reset-button will once again set the relative screen pattern position to 0, which means the indication "sad man".
The temperature recorder can easily be applied e.g. on different receptacles by using threads, gluing or fixing the recorder permanently in another way, or to be used flexibly a loop can be fixed around the pipe for easier handling, reading.
The temperature recorder consists of a cylindrical transparent pipe, tubular cover or box 1 having an inside piston 2 in the form of a rod or a pipe, which runs within the exterior tubular cover. A thermally conductive seat 3 is placed at the bottom of the tubular cover 1 and is preferably made from aluminium.
A bimetal washer having a determined range of temperature changes (by hysteresis settled sudden change)4 is fixed in the seat of aluminium 3. A screen pattern 5 is formed on the inner wall of the exterior tubular cover 1b in the form of an even number of horizontal lines, preferably being coloured with a transparent margin between them. This screen pattern reaches from the bottom of the tubular cover to the top and preferably covering the entire inner wall 1b of the tubular cover.
A follower pin 6 will be hit by the bimetal washer 4 when it changes its form from convex to concave at a given temperature. The piston 2 will then be pushed vertically (by the pin) to a determined level, the movement hereby being stopped by a lid 7.
The diameter of the piston is so adapted to the diameter of the tubular cover that there is a certain friction when the piston is moved within the tubular cover, this friction being a braking means for the piston (inertia) which means that the piston does not change its position when the temperature recorder is shaken or hit by a stroke. A cylinder shaped magnet 8 is fixed on the upper end of the piston. A screen pattern 9 is formed on the surface of the piston with horizontal lines with a face displacement in the middle of the screen pattern. This screen pattern consists of horizontal lines having preferably two different colours and/or two different pictures formed by lines on a white or different coloured bottom. This is a colour which differs from the two inside screen patterns.
When the bimetal washer changes its form at the given temperature, a vertical movement of the piston will be released and from a screen pattern picture 10 shown in the original position on half of the screen pattern surface, a new picture is now shown on the other screen pattern surface 11. The piston will reach a stop level by the lid 7.
In order to reset the piston with the screen pattern picture 11 visible, a button 12 is pressed. This button 12 has also a magnet within the upper part 13 of its lid. When this button 12 is pressed the magnets will repel each other so that the piston 2 with the screen pattern picture 10 again reaches its original position.
Further there is a lid 16 in the tubular cover 1 which limits the highest position of the piston in the tubular cover 1. Hereby the piston 2 is pressed with its upper end against the lid 16 via a spring 17. There is a button 19 in the upper end of the tubular cover 1, which button can be pressed downwards against a spring 18. The springs 17 and 18 are preferably so balanced that there is equilibrium between those springs when the piston 2 has reached its uppermost position caused by the force from the change of form of the bimetal. When the bimetal is to return to its original form, the button 19 is pressed and the piston is returned to its original position. This embodiment uses a bimetal means which has a great hysteresis, that means that the temperature difference between the sudden change temperature and the return temperature is considerable. Preferably the return temperature, that is the temperature when the bimetal returns to its original form, is lower than the lowest temperature in the surroundings during the use of the temperature recorder. It is hereby secured that the piston will be returned by manual operation of the button 19.
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